This invention relates to a controlled release delivery system of solid dosage forms with a plurality of controls on the release of the active ingredient or ingredients.
Controlled release delivery systems have been of interest to many researchers, especially in pharmaceutical industry. Controlled release includes slow release or programmed release. There are several advantages in using controlled release dosage forms. For instance, a patient may need to take certain tablet three times a day. With a slow release dosage form, the patient may only need one tablet a day. Another example is that enteric-coated tablets are useful to protect the active ingredient against gastric fluid and release the active ingredient only in the intestine.
In pharmaceutical of solid dosage form, there have been many different versions of controlled release systems. More popular controlled systems are matrix system, membrane controlled system, membrane controlled with one or more orifices. Membrane controlled delivery systems developed by Alza pharmaceutical are becoming more popular. Tegretol(copyright)-XR (by Novartis Pharmaceuticals) and Procardia XR(copyright) (by Pratt Pharmaceutcals, Division of Pfizer) are two examples of controlled release products made by Alza""s membrane controlled system.
Drug release in a membrane system is basically controlled by osmotic pressure due to the concentration gradient. The matrix system also uses concentration gradient except the active ingredient is blended or waged in the polymer matrix. All of these systems are basically controlled by one major driving force.
One of the outstanding controlled release system, different from the above systems, is sometimes called a xe2x80x9cpush-pullxe2x80x9d system also developed by Alza Pharmaceutical (U.S. Pat. No. 5,091,190 Feb. 25, 1992). In this system, there are two compositions in a lumen, one contains the active ingredient and the other contains a hydrogel. The two compositions are arranged in a two-layered format and coated by a membrane, wherein an orifice is made only on one side, the side with composition containing active ingredient. One representative example is Glucotrol XR(copyright) (by Pratt Pharmaceuticals, Division of Pfizer). This prior art has two driving forces to release the active ingredient: (1) the water penetrating through the membrane swells or dissolve both compositions, generating osmotic pressure in the lumen and push the composition out through the orifice, and (2) the water in the lumen swells the hydrogel, which expands and push other composition out through the orifice on the other side of the coated tablet.
There are several problems with this push-pull system. First, the membrane must have one or more than one orifices usually drilled by an expensive laser drill or other mechanical drill. Secondly, the orifices must be made on the particular side of the tablet. Otherwise the delivery system will not function properly. Therefore, additional process is needed to arrange the tablets in the specific orientation before the tablets can be drilled. Thirdly, some of the active might be waged into the hydrogel as the hydrogel is swollen, thus, increasing the complexity in the development of the dosage form. Yet another potential problem is that both compositions are directly contacting the same membrane, therefore swelling of the hydrogel starts immediately, and it may be difficult to achieve a delayed release profile. In other words, the two driving forces start at about the same time.
This invention is particularly designed to improve the current delivery systems for solid dosage forms, especially the push-pull system in U.S. Pat. No. 5,091,190. The delivery system in this invention does not need to be drilled, thus, saving time and reducing costs. The delivery system in this invention does not have a direct contact between any two compositions because of the additional membrane in between, thus, easier to develop. Different from the Push-Pull system, which consists of two compositions in a membrane, this invention comprises a compartment-in-compartment design. In this invention, the main compartment is confined by a membrane, and the sub-compartment or sub-compartments inside the main compartment, are also confined by a membrane. This design makes the delivery system more versatile than any known prior arts.
In addition to the above advantages, this invention has a plurality of controls in releasing the drug composition or compositions. The driving force for each control can be initiated at different point of time. Therefore, this invention is more flexible and more versatile in developing a controlled release dosage form suitable for a variety of situations.
Unlike most controlled release system, where the release of drug composition or compositions is primarily controlled by one or two driving forces, the delivery system in this invention may comprise a plurality of controls on the release of drug composition or compositions.
Unlike a push-pull system, wherein both of the two compositions are confined in a membrane, i.e., in one compartment, the delivery system in this invention comprises one main compartment and one or a plurality of sub-compartments. Unlike a Push-Pull system, wherein there are two compositions, with the active in active ingredient in one composition and hydrogel in the other composition, this invention comprises one or more than one active ingredients in each of the compartments (main compartment or individual sub-compartment). Yet another important aspect of this invention is that it comprises different kinds of driving forces and these driving forces may be initiated at different points in time. Therefore, this invention discloses a superior delivery system suitable for the development of controlled release solid dosage forms.